Will a person be held accountable for what he said aloud to himself only?

Accountability for sins and mistakes is a good and commendable act, and it is the practice of the righteous. It was narrated from Umar ibn al-Khattab, may Allah be pleased with him, that he said: "Hold yourselves accountable before you are held accountable."

As for what a person says to himself (self-talk), he is not held accountable for it as long as he does not speak it aloud. It is forgiven and will not be exposed.

However, what the tongue utters or the limbs do intentionally, as well as the actions of the heart, are recorded in one's scroll. If he repents from it, his Lord forgives him, erases his bad deeds, replaces them with good deeds, and conceals him in the Hereafter. If he does not repent, then he is under the will of Allah.

The texts indicate that Allah will not expose the believer for his sins on the Day of Judgment; rather, He will conceal him and forgive him, as stated in the Hadith of Ibn Umar, may Allah be pleased with them both, from the Prophet, peace and blessings of Allah be upon him.

What the questioner refers to regarding his self-accountability is not a sin; rather, it is a praiseworthy act for which he will be rewarded.